Conventionally, as a measuring apparatus which measures a distance between multiple different points and arrangement (alignment) of each part of an object to be measured, there is known a system that magnifies an image of the part to be measured with an optical lens system (microscope), outputs thus magnified image as a video signal, and displays the magnified image on a display unit.
FIG. 12 is a schematic configuration diagram of such conventional measuring apparatus as described above. Reference numeral 101 indicates the object to be measured, and it is placed on stage 102. Reference numeral 105 indicates a microscope tube, and multiple optical lenses are installed therein. Reference numeral 106 indicates an image sensor, which captures an image of a measured portion of the object to be measured 101 through the optical lenses, converts the image into electrical signals, and then transmits the signals to the display unit 107. The display unit 107 displays on display screen 108, a magnified image of the measured portion of the object to be measured 101. Scales for length measurement are superimposed on the image in the display screen 108, or the image is processed by an image processor, whereby it is possible to measure a distance from a reference point to a point to be measured in the measurement area on the object 101. In FIG. 12, for ease of explanation here, a character “A” is shown on the side surface of the object to be measured 101. However, in practice, the character “A” is described on the upper surface of the measurement area of the object to be measured 101. As is shown in FIG. 12, the character of “A” on the measurement area of the object to be measured 101 is magnified and displayed on the display screen 108.
With reference to FIG. 13A and FIG. 13B, the conventional measuring apparatus as described above will be explained, for example, in the case where it is used as a measuring apparatus to inspect the mounting status (alignment) of a suspension flexure for a hard disk or the like.
FIG. 13A shows a configuration of a suspension part of a hard disk, in which beam 3 is connected to base plate 2 via a hinge 7. Flexure 5 is mounted on the beam 3, in such a manner as coming into contact with dimple 3a provided on the beam 3. The flexure 5 is provided with pad 5a. Reference numeral 4 indicates a tentative standard hole, and numeral 6 indicates a boss hole. In inspecting the mounting position of head part of the hard disk, it is necessary to measure accurately, distance Lm (=Lc+Lv), which is a distance between the pad 5a and the center of the boss hole 6, and the mounting position of the pad 5a. FIG. 13B shows an example of TV monitor screen to perform measurement.
In the inspection of such precision component, a highly precise measurement is required. Therefore, in many cases, magnification of the image is set to be high. FIG. 13B shows a display screen when the magnification is set to be high, and the boss hole 6 extends off the screen view. In such a case above, it is impossible to directly measure the distance Lm between the pad 5a and the center of the boss hole 6. It is not possible either to directly measure the mounting position (alignment) of the pad 5a with respect to the line connecting the center of the boss hole 6 and the center of the tentative standard hole 4. As thus described, in the conventional measuring apparatus, if the rate of magnifying the image is raised in order to improve the measuring precision, the entire measuring point cannot be fitted into the screen view, and thus measuring a distance between desired two points and measuring alignment are not possible on the screen. In order to enhance the measurement precision, it is alternatively possible to employ a multi-pixel CCD, other than raising magnification, but this may render the system expensive.
Therefore, when the conventional system as described above is employed, Lv is measured using another point existing in the screen view (here, the center of tentative standard hole 4) as a tentative reference point. Lc, which is a distance between the center of the tentative standard hole and the center of the mounting hole, is preexamined according to a design value. Lv is measured assuming that this Lc is constant, and Lm is obtained from the measured value Lv (Lm=Lv+Lc).
However, since the distance between the center of the tentative standard hole 4 and the boss hole 6 may vary depending on degree of processing accuracy and assembling accuracy, it is not constant to be exact. Consequently, a result of measurement with high precision cannot be obtained.
As an example of a measuring method to solve the above problems, JAPANESE PATENT APPLICATION LAID OPEN (KOKAI) H07-139924 discloses a method for measuring two points simultaneously on an electronic component. In this particular example, two image sensors respectively capture images of two points. Therefore, requirements of two image sensors may cause a cost increase for the apparatus.
JAPANESE PATENT APPLICATION LAID OPEN (KOKAI) H11-37720 discloses a measuring method in which images of respective points are obtained by independent two optical systems. Therefore, even if the magnification of the optical system is set higher, the images will not extend off the view of the optical system. However, this method requires two lens systems and two image sensor systems, thereby rendering the configuration of the apparatus complicated, also causing cost increase for the apparatus.
In addition, if the conventional apparatus is used, it is not possible to accurately measure the mounting position (alignment) of the pad 5a, with respect to the line connecting the center of the boss hole 6 and the tentative standard hole 4.
The present invention has been made considering the above problems, and its purpose is to provide an apparatus and a measuring method which achieve a measurement of distances (dimensions) between multiple points at multiple locations on the object to be measured, and mounting angle and arrangement (alignment) of each part on the object to be measured, by use of one optical system and one screen. In addition, another purpose of the present invention is to provide a measuring apparatus and a measuring method with which it is possible to handle the case where multiple points at multiple locations on the object to be measured are respectively provided on both front surface and back surface.